The invention relates to a detachable connecting device for connecting at least two toy-construction elements each being provided with a bore, a socket defined for introduction into the bore of the structural elements which has a cylindrical shaft section and at one end longitudinal slots for achieving a radial elasticity, and which at its free end is provided with a radially protruding small outerledge shoulder defined to lock the one structural element positively after the introduction of the socket into the bore of the structural elements, as well as an engagement flange at the end of the cylindrical shaft section facing away from the edge shoulder.
A detachable connecting device of the aforementioned type is known from Swiss Patent Number 655,247. In accordance with this patent two toy-construction elements which have to be connected with each other are provided each with a cylindrical bore and are connected to each other by a substantially cylindrical socket extending through the two bores. In one of its end areas the socket is provided with two longitudinal slots which cause a radial elasticity of this end area. The socket is provided at its slotted end with a radial outer edge shoulder. In the opposite end area the socket is provided with an outer annular like flange. Moreover, the two construction elements which have to be connected with each other are each provided at the outer side of their bores with an annular like recess. For connecting the two interengaging construction elements the socket with the edge shoulder end is pushed through the bore of the two construction elements, which is made possible due to the radial elasticity of the slotted end area of the socket. In the end position of the socket the edge shoulder of the socket locks into the annular recess of the one construction element, while the annular like flange of the socket engages the annular like recess of the other construction element, so that the two construction elements are held together by the socket.
A further embodiment of a detachable connection device of the aforementioned type is known from Swiss Patent Number 658,887. In accordance with this patent a socket of the aforedescribed type is formed as a double socket in that the socket is slotted and is provided with an outer edge shoulder at both ends whereby the mentioned annular like flange is mounted in the longitudinal center of the socket. Such a socket is used to detachably connect two construction elements, whose bore ends are provided with annular like recesses on both wall faces of each construction element.
These known and commercially available connection devices are detachable in that two connected construction elements may be pulled apart by overcoming the spring force of the slotted elastic end of the socket on the edge shoulder. However, such devices have a disadvantage in that detachment may occur unintentionally if, during an operation mode, a separating force is applied to a construction element containing such a connecting device.
It is therefore an object of the invention to provide a detachable connection device of the aforementioned type which enables, with a simple actuation, a clear locking of the socket or a clear release of the socket on the construction elements being connected therewith.
This object is attained in accordance with the present invention by providing a bolt like locking element inserted into the socket which is movable between two positions relative to the socket, whereby in the first position an end section at the free end of the locking element engages the inner face in the area of the radial plane of the edge shoulder and in the second position is spaced from the inner face of the socket in the area of the radial plane of the edge shoulder.
From Swiss Patent Number 609,752 a mounting element for detachably connecting two pieces of sheet metals are known. The mounting element consists of eye and pin parts which are injection molded in one piece with nominal breaking point locations. In the initial position the pin part is protruded axially from a central bore of the eye. At its one end the eye has an engagement flange. Adjacent to the flange it is provided with a rectangular circumferential groove in its cross section and in the axial section.
Two straddling jaws are provided adjacent to the circumferential groove. The jaws are rectangular in cross section and are tapered in a wedge like fashion at their free ends. The cross section of the straddling jaws extend on all sides of the cross section of the circumferential groove. For assembling purposes the mounting element is inserted at first through a rectangular opening in the first sheet metal, whose cross sectional dimensions are larger than the cross section of the groove but smaller than the cross section of the straddling jaws. While the pin part is removed from the central bore of the eye, the straddling jaws can yieldingly engage, so that the first sheet metal snaps into the groove. Subsequently, the pin part is inserted axially into the central bore after separating the nominal breaking locations, wherein it is held axially nondisplaceable by means of a snap element and thereby securing the eye permanently on the first sheet metal. The straddling jaw may then be inserted through a larger rectangular opening of the second sheet metal. A rectangular end section of the pin part engages between the two straddling jaws. By turning the pin part the two straddling jaws can be spread from their untensioned positioned, so that their side walls are forcibly locked in the opening of the second sheet metal.
This known mounting element is not suitable for toy construction elements, because it is permanently snapped in on the first sheet metal and because it requires two differently shaped sizes of holes in the two pieces of sheet metals. Further, the mounting element is not suitable for centering the two pieces of sheet metals with respect to each other, because the first piece of sheet metal has free play in the groove. Therefore, the two pieces of sheet metals must be centered with respect to each other by additional parts. While the straddling jaws only engage tensionally in the opening of the second sheet metal a precise interengaging position of the two pieces of sheet metals is not assured. When the mounting element remains for a long period of time in the straddled position, they lose their elasticity due to "creep" of the synthetic materials. Under these circumstances even when the pin part is returned to its release position, the straddling jaws remain in their straddled position and the mounting element can only be removed from the opening of the second sheet metal piece with considerable difficulty and often with destroying the pin. A further disadvantage of this known mounting element is that it protrudes substantially at the rear face of the second sheet metal piece. This makes the device additionally unsuitable for use with toy-construction elements.
A similar mounting element with the same disadvantages is disclosed in Swiss Patent Number 591,638. In contrast to the aforementioned mounting element the pin part in this case is displaced axially between a locking position and a release position, instead of being turned. In addition, the two differently sized openings in the sheet metal pieces to be connected are cylindrical instead of rectangular.